A supercharger is an apparatus to increase the intake pressure of an internal combustion engine (hereinafter referred to as “engine”), and to improve the filling efficiency thereof. Conventionally, in a case where torque required of the engine is great, supercharging is performed using the supercharger and thereby the torque generated by the engine is increased.
Superchargers are roughly classified into a turbocharger to be driven by the exhaust gas from the engine, and a mechanical-driven supercharger to be driven by the engine or an electric motor.
In addition, a power-assisted supercharger drives a rotary shaft of the turbocharger by using an electric motor, in order to enhance (assist) the torque or the rotational speed of the turbocharger. This power-assisted supercharger is disclosed in, for example, Patent Documents 1 to 3.
Conventionally, in order to determine drive requests to the electric motor of the power-assisted supercharger, the acceleration intention of the driver thereof is detected from the amount of movement of an accelerator pedal or the like, a target value of a boost pressure or a turbine rotational speed is calculated, a difference between the target value and an actual value of the boost pressure or the turbine rotational speed is detected, and feedback control is performed using the difference.